A periprosthetic joint infection represents a devastating complication, may be difficult to eradicate, and may impair the quality of life of the patient. In the study by Zmistowski and colleagues, the authors asked whether the quantity of life, or life expectancy, was altered in patients surgically treated for a periprosthetic joint infection as compared with patients undergoing revision surgery for aseptic reasons. The authors also asked whether there were factors predictive of mortality that could be identified in the group of patients with periprosthetic joint infection. The answers to both questions are important and worthy of investigation.

From the authors’ institutional database from January 2000 to March 2010, 2955 patients were identified as having undergone either a revision hip or knee arthroplasty. Using a modification of the Musculoskeletal Infection Society’s definition of periprosthetic joint infection (the authors’ institution does not utilize histological analysis as a diagnostic criterion for infection), 436 patients were identified as having undergone revision surgery for a diagnosed infection. The remaining 2342 patients who underwent revision surgery for all other causes were used as a comparison group. The risk of mortality was assessed for both groups. For the group of patients with periprosthetic joint infection, a multivariate analysis was subsequently performed. The authors showed, in answer to their first question as to whether quantity of life is altered, that mortality was increased at one year in patients treated for infection compared with patients undergoing an aseptic revision. An increase of more than fivefold in the risk of death was found for patients treated surgically for a periprosthetic joint infection. Relative to the authors’ second question of factors predictive of mortality, the study showed that increasing age, a worse preoperative status (as evaluated by the Charlson Comorbidity Index), and a history of stroke or cardiovascular disease or being treated for a polymicrobial infection were predictive of an increased risk of mortality. This information is important for the clinician and makes rational sense; clearly, both the burden of infection and the treatment of an infection may influence mortality. This study raises two questions. Is the surgical intervention required to treat a periprosthetic joint infection comparable in morbidity with the surgical intervention required in an aseptic revision? Are all infections comparable in the health burden with the host?

Is the magnitude of the surgical procedure itself an explanation for the increased death rate identified in the population with periprosthetic joint infection? The study was not designed to compare the specific type of surgical treatment chosen for the individual patients in the periprosthetic joint infection group (i.e., irrigation, debridement, and liner exchange; single-stage component removal and reimplantation; or two-stage component removal and later reimplantation) with the revision surgery performed for the individual patients in the aseptic group (head and liner exchange, one-component revision, or two-component revision). Any surgical intervention inherently has a relative associated morbidity (up to and including mortality) and places a burden on the patient’s current health; this health burden may be difficult to quantify, yet one could rationally assume that for either group the morbidity would be greatest in a two-component exchange and the least in a liner exchange. Answering specifically whether the mortality rate identified in patients with periprosthetic joint infection is influenced by the surgical treatment chosen needs further investigation.